Anti-coring needle

ABSTRACT

A hypodermic needle comprising a tubular, elongated, generally cylindrical wall defining an internal longitudinal bore extending longitudinally therethrough along a longitudinal axis, The longitudinal bore has forward and rearward openings. The cylindrical wall is constructed and arranged to form a forward pointed end and a rearward pointed end. The rearward pointed end is defined by an annular end surface forming the rearward end of said cylindrical wall. The rearward pointed end terminates in a rearwardmost point lying in an imaginary plane disposed perpendicularly to the longitudinal axis. The annular rearward end surface defines an imaginary plane inclined with respect to the imaginary plane perpendicular to the longitudinal axis. The cylindrical wall has a laterally facing opening spaced from the rearward opening of the longitudinal bore, and the longitudinal bore is restricted at a position between the rearward opening and the laterally facing opening.

The present invention relates to hypodermic needles, and moreparticularly, to the type of hypodermic needles that have a rearward endadapted to establish fluid communication with a medicament prior to aninjection operation.

Hypodermic needles have several applications. In most such applicationsthe hypodermic needle has a forward end adapted to penetrate the skin ofan individual, and a rearward end adapted to communicate with a liquidmedicament source so that the medicament is permitted to travel from thesource, through a central longitudinal bore in the needle, and into theflesh of the individual.

In many of the applications for hypodermic needles, it is necessary forthe rearward end of the needle to puncture a seal in order to establishfluid communication with the medicament source. For example, oneapplication exists in the field of automatic injection devices, whereina liquid medicament is sealed within a tubular container, preferablymade of glass, having a synthetic rubber seal closing off a forward endthereof. During an injection operation, the rearward end of the needlepunctures the seal to establish fluid communication with the medicament,and a stressed spring assembly is released so as to cause the forwardend of the needle to project outwardly from the forward end of automaticinjector body and into the flesh of an individual while such fluidcommunication is maintained. A plunger rearwardly confines themedicament within the container and is driven by the released springassembly towards the forward end of the container and functions to forcethe medicament through the needle and into the flesh of the individual.Such automatic injection devices are disclosed, for example, in U.S.Pat. Nos. 5,391,151; 5,102,393; and copending U.S. patent applicationSer. No. 08/545,149 filed Oct. 19, 1995, now U.S. Pat. No. 5,658,259,which are hereby incorporated by reference.

A problem associated with the aforementioned arrangements in which therearward end of the needle must puncture a rubber or other type of sealin order to establish fluid communication with a medicament is that itis possible for the rearward end of the needle to core out or dislodge asmall particle from the seal. This can lead to problems associated withthe needle establishing fluid communication with the medicament. Forexample, where a synthetic rubber seal is used, a synthetic rubberparticle may become lodged in the needle's rearward end andsignificantly reduce the amount of medicament flow through the needle.While certain types of "anticoring" rubber materials, such as naturalrubber, have been used, such materials are not compatible with as manytypes of medicaments in comparison with synthetic rubber.

To obviate the aforementioned problems, there has been proposed ahypodermic needle in which a second, lateral opening is provided in thecylindrical side wall of the needle, towards the rearward end of theneedle. The purpose of providing a second opening is to enable fluid toflow freely through the needle even in the event that the rearwardopening is plugged with a rubber particle. However, this configurationdoes not address the potential for a relatively small rubber particlefrom entering the rearward end of the needle and becoming lodged withinthe bore of the needle at, or downstream from, the lateral secondopening, thus impeding fluid flow through the needle. It also does notaddress another problem which may arise when a lateral second opening isprovided. More specifically, rather than a particle becoming completelydislodged from the rubber seal, in some instances the particle maybecome tethered to the seal at the point of puncture. In such instances,it is possible for the tethered particle to be drawn partially into thesecond, lateral opening so as to partially block the longitudinalpassage through the needle and thereby reduce flow through the needle.It may also be possible for a dislodged particle to partially enter thesecond, lateral opening and thereby reduce flow through the needle.

It is an object of the present invention to provide a hypodermic needlethat overcomes the problems noted above. In accordance with the presentinvention, there is provided a hypodermic needle comprising a tubular,elongated, generally cylindrical wall defining an internal longitudinalbore extending longitudinally through the cylindrical wall along alongitudinal axis. The longitudinal bore has forward and rearwardopenings. The cylindrical wall is constructed and arranged to form aforward pointed end and a rearward pointed end. The rearward pointed endterminates in an annular end surface having a rearwardmost point lyingin an imaginary plane disposed perpendicularly to the longitudinal axis.The annular rearward end surface defines an imaginary plane inclinedwith respect to the imaginary plane perpendicular to the longitudinalaxis. The cylindrical wall has a laterally facing opening spaced fromthe rearward opening of the longitudinal bore, and the longitudinal boreis restricted at a position between the rearward opening and thelaterally facing opening.

These and other objects, features, and advantages of the presentinvention will become apparent from the following description and theappended claims, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of the hypodermic needleaccording to the principles of the present invention;

FIG. 2 is an enlarged longitudinal sectional view of the rearwardportion of the hypodermic needle in accordance with the principles ofthe present invention;

FIG. 3 is a plan view of the rearward portion of the hypodermic needleof the present invention, rotated 90° about the longitudinal axis withrespect to FIG. 2;

FIG. 4 is a transverse sectional view taken through the line 4--4 inFIG. 1;

FIG. 5 is a transverse sectional view taken through the line 5--5 inFIG. 1;

FIG. 6 is a longitudinal sectional view showing the hypodermic needle inaccordance with the present invention, being utilized in conjunctionwith a dental cartridge assembly of an automatic injector assembly inaccordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now, more particularly, to the drawings, there is shown inFIG. 1 a hypodermic needle, generally indicated at 10, in accordancewith the principles of the present invention. The hypodermic needlecomprises a tubular, elongated, generally cylindrical wall 12 definingan internal longitudinal bore 14 extending longitudinally therethroughalong a longitudinal axis (indicated at x in FIG. 2). The longitudinalbore 14 has a forward opening 16 and a rearward opening 18. Preferably,the cylindrical wall 12 is made from type 304 stainless steel. Thecylindrical wall has a forward pointed end, generally indicated at 20formed by an angular grind. The cylindrical wall also has a rearwardpointed end, generally indicated at 22, also formed by an angular grind.The rearward pointed end 22 is defined by and terminates in an annularend surface 24. As shown more clearly in FIG. 2, the rearward pointedend 22 terminates in a rearwardmost point 26 lying in an imaginaryplane, indicated at 28, disposed perpendicularly to the longitudinalaxis x. The annular rearward end surface 24 defines an imaginary plane,indicated at 32, inclined with respect to the imaginary plane 28perpendicular to the longitudinal axis x.

The cylindrical wall 12 has a laterally facing opening 34 spaced fromthe rearward opening 18 of the longitudinal bore 14. As can beappreciated from the figures, the lateral opening 34 is in longitudinalalignment with the rearwardmost point 26. The cylindrical wall 12 iscrimped or otherwise extended inwardly into the longitudinal bore 14 toform a restriction 38, which restricts the longitudinal bore 14 at aposition between the rearward opening 18 and the laterally facingopening 34.

As shown in FIG. 3, the lateral opening 34 is defined by an oblongsurface, generally indicated at 40, defining a beveled edge surroundingthe opening 34. The surface 40 defining the beveled edge converges as itapproaches the longitudinal axis of the hypodermic needle.

From FIGS. 2 and 3, it can be appreciated that the more forwardlydisposed portion 42 of surface 40 is inclined at a smaller angle withrespect to the longitudinal axis x in comparison with the rearwardportion 44 of surface 40. While the forwardly disposed surface portion42 is substantially flat and forms an angle θ, preferably in the rangeof about 28°±1° with respect to the longitudinal axis, the rearwardportion 44 is substantially arcuate so as to define an imaginary circlehaving a maximum radius R of 0.0060 inches.

The imaginary plane 32 defined by the annular end surface 24 forms anangle α with respect to the imaginary plane 28. Angle α is preferablyabout 30°±1°. The rearwardmost point 26 is disposed at a distance g fromthe center of the restriction 38. Preferably, the distance g isapproximately 0.030 inches. The rearwardmost point 26 is disposed at adistance h from the closest edge forming the lateral opening 34.Preferably, the distance h is approximately 0.052±0.002 inches. Thelongitudinally rearwardmost and longitudinally forwardmost portions ofthe surface 40 forming the lateral opening 34 are spaced by a distancei. Preferably, the distance i is approximately 0.024±0.003 inches. Thecrimped or inwardly extending surfaces forming the restriction 38 areseparated by a distance j. Preferably, the distance j is approximately0.005+0.001 to -0.002 inches. The thickness of the cylindrical wall isdesignated by reference character t. Preferably the thickness t is about0.0050+0.0010 to -0.0015 inches.

Referring to FIG. 4, which is a sectional view taken through the line4--4 in FIG. 1, it can be appreciated that the outer diameter for themajor portion of the cylindrical wall 12 is a dimension k, which ispreferably about 0.016-0.0165 inches (27 gauge). As can also beappreciated from FIG. 4, the cylindrical wall 12 has an inner diameterl, which is preferably between about 0.0075 and 0.0090 inches.

Referring now to FIG. 5, which is a sectional view taken through theline 5--5 in FIG. 1, it can be appreciated that surfaces 46 forming theside surfaces leading to the forwardmost point 48 of the hypodermicneedle are inclined by an angle β with respect to an imaginary plane 50through axis x, as shown. In FIG. 1, it can be seen that the forwardmostpoint 48 is disposed on the opposite side of the needle (i.e., out oflongitudinal alignment) with respect to rearwardmost point 26.

FIG. 6 is a longitudinal sectional view of the hypodermic needle of thepresent invention shown in cooperation with a dental cartridge assemblyof an automatic injector. The dental cartridge assembly, generallyindicated at 60 includes a glass container 62, a forwardly disposedrubber sealing disc 64, a metallic clamp ring 66, and a needle hubassembly 68. The clamp ring 66 is crimped around the forward end of theglass container 62 so as to enable the rubber sealing disc 64 to form aforward seal for medicament 70 contained within the glass container 62.The needle hub assembly 68 is fixed to the needle 10 at a position 72 byan epoxy or any conventional fashion. During an injection operation, theneedle hub assembly 68 is caused to ride rearwardly with respect to theglass container 62 into the position shown in FIG. 6. During thismovement of the needle hub assembly 68, the rearward pointed end 22 ofthe hypodermic needle 10 is caused to puncture the rubber sealing disk64. The specifics of the injector device of this type can be more fullyappreciated from co-pending U.S. patent application Ser. No. 08/280,884,abandoned, hereby incorporated by reference, and the aforementionedincorporated U.S. Pat. No. 5,102,393 and U.S. patent application Ser.No. 08/545,149 filed on Oct. 19, 1995.

As shown in FIG. 6, the puncturing force of the hypodermic needle 10 hascreated a tethered rubber particle 76. Such tethered particle 76 willordinarily be formed on a side of the needle opposite the rearwardmostpoint 26. The lateral opening 34 is preferably positioned generally onthe same side of the needle as the rearwardmost point and mostpreferably the lateral opening 34 and rearwardmost point 26 are inlongitudinal alignment with one another so that the tethered particle 76will not interfere with the opening 34.

In many instances, the particle will be captured within the rearwardopening 18 of the hypodermic needle, as generally indicated in thedashed line configuration 80, rather than being tethered as withtethered particle 76. Where the particle 80 becomes lodged in therearward opening 18, the particle remains at such position, rather thanbeing permitted to float within the medicament and perhaps find its wayto the laterally facing opening 34, wherein it may block the bore 14 andseverely restrict flow of medicament through the needle. The restriction38 is provided in the cylindrical wall 12 in order to prevent anyfurther forward travel of the particle through the bore 14 so that theparticle does not become lodged within the bore at a more downstreamposition wherein it may completely prevent fluid flow. With the rearwardopening 18 now substantially blocked by the particle, the medicamentwill flow into the bore 14 via the opening 34.

It should also be noted that the oblong shape of lateral opening 34minimizes the likelihood of complete blockage thereof by a dislodgedparticle. In addition, the surface 40 and opening 34 are shaped so thatthey will not cause any further coring of the seal 64. Morespecifically, the arcuate rearward portion 44 (preferably defining animaginary circle having a maximum radius of 0.0060 inches) is shapedsuch that the portion of the rubber seal 64 surrounding the puncturehole, and that slides along the exterior periphery of the cylindricalwall 12 as the rearward portion of the needle is moved through the seal64, will be readily and smoothly accommodated. In addition, the gentlysloping forward portion 42 (preferably forming an angle of about 28°±1°with respect to the longitudinal axis x) will gently expand the portionsof seal 64 surrounding the puncture hole as such portions ride forwardlyalong the portion 42 as the needle is further extended into thecontainer, without any rough or sharp edges of the needle cutting orbiting into the seal 64.

While the hypodermic needle of the present invention has been describedin conjunction with an automatic injector, it should be appreciated thatthis hypodermic needle has several other applications in the medicalindustry, such as syringes.

It thus will be seen that the objects of this invention have been fullyand effectively accomplished. It will be realized, however, that theforegoing preferred specific embodiment has been shown and described forthe purpose of this invention and is subject to change without departurefrom such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

What is claimed is:
 1. A hypodermic needle comprising:a tubular,elongated, generally cylindrical wall defining an internal longitudinalbore extending longitudinally through the cylindrical wall along alongitudinal axis, said cylindrical wall forming a forward end defininga forward opening of said bore and a rearward end defining a rearwardopening of said bore, said forward end having a point constructed andarranged to pierce an individual's flesh, said rearward end having anannular end surface and a rearwardmost point lying in an imaginary planedisposed perpendicularly to said longitudinal axis, said annularrearward end surface defining an imaginary plane inclined with respectto said imaginary plane perpendicular to the longitudinal axis, saidcylindrical wall having a laterally facing opening spaced closer to therearward opening of said longitudinal bore than the forward opening ofsaid longitudinal bore, and said longitudinal bore being restricted at aposition between said rearward opening and said laterally facingopening.
 2. The hypodermic needle according to claim 1, wherein saidlaterally facing opening is generally in longitudinal alignment withsaid rearwardmost point.
 3. The hypodermic needle according to claim 2,wherein said cylindrical wall has a relatively narrower inner diameterat said position of said bore between said rearward opening and saidlaterally facing opening in comparison with other positions of said boreso that said longitudinal bore is restricted at said position betweensaid rearward opening and said laterally facing opening in comparisonwith said other positions.
 4. The hypodermic needle according to claim1, wherein said forward end has a forwardmost point disposed on anopposite side of said cylindrical wall with respect to said rearwardmostpoint of said rearward end.
 5. The hypodermic needle according to claim2, wherein said laterally facing opening is defined by an oblong-shapedsurface defining a beveled edge surrounding said laterally facingopening.
 6. The hypodermic needle according to claim 5, wherein aforwardly disposed portion of said oblong-shaped surface is inclined ata smaller angle with respect to said longitudinal axis in comparisonwith a rearwardly disposed portion of said oblong-shaped surface.
 7. Thehypodermic needle according to claim 6, wherein said forwardly disposedportion of said oblong-shaped surface forms an angle in a range of about27° to about 29° with respect to said longitudinal axis.
 8. Thehypodermic needle according to claim 6, wherein said rearwardly disposedportion of said oblong-shaped surface is substantially arcuate so as todefine an imaginary circle having a maximum radius of 0.0060 inches. 9.The hypodermic needle according to claim 7, wherein said rearwardlydisposed portion of said oblong-shaped surface is substantially arcuateso as to define an imaginary circle having a maximum radius of 0.0060inches.
 10. The hypodermic needle according to claim 1, wherein saidimaginary plane comprising said annular end surface of said rearwardpointed end is disposed at an angle in a range of about 29° to about 31°with respect to said imaginary plane disposed perpendicularly to saidlongitudinal axis.
 11. The hypodermic needle according to claim 1,wherein said rearwardmost point of said rearward end is disposed adistance of about 0.030 inches from a center of said restricted positionof said longitudinal bore.
 12. The hypodermic needle according to claim11, wherein said rearwardmost point of said rearward end is disposed adistance in a range of about 0.050 to about 0.054 inches from a closestedge forming said laterally facing opening.
 13. The hypodermic needleaccording to claim 1, wherein said cylindrical wall has a thickness in arange of about 0.003 to about 0.006 inches.